2. put class-tgm-plugin-activation.php file to root folder of your theme and create /plugins folder where you should put motopress-content-editor.zip file.

3. go to edit functions.php file of your theme and add settings for TGM Activation class and hook them to the tgmpa_register action.

/**
* Include the TGM_Plugin_Activation class.
*/
require_once dirname( __FILE__ ) . '/class-tgm-plugin-activation.php';
add_action( 'tgmpa_register', 'my_theme_register_mpce_plugins' );
/**
* Register the required plugins for this theme.
*
* The variable passed to tgmpa_register_plugins() should be an array of plugin
* arrays.
*
* This function is hooked into tgmpa_init, which is fired within the
* TGM_Plugin_Activation class constructor.
*/
function my_theme_register_mpce_plugins() {
/**
* Array of plugin arrays. Required keys are name and slug.
* If the source is NOT from the .org repo, then source is also required.
*/
$plugins = array(
// This is an example of how to include a plugin pre-packaged with a theme
array(
'name' => 'MotoPress Content Editor', // The plugin name
'slug' => 'motopress-content-editor', // The plugin slug (typically the folder name)
'source' => get_stylesheet_directory() . '/plugins/motopress-content-editor.zip', // The plugin source
'required' => true, // If false, the plugin is only 'recommended' instead of required
'version' => '1.5.9', // E.g. 1.0.0. If set, the active plugin must be this version or higher, otherwise a notice is presented
'force_activation' => false, // If true, plugin is activated upon theme activation and cannot be deactivated until theme switch
'force_deactivation' => false, // If true, plugin is deactivated upon theme switch, useful for theme-specific plugins
'external_url' => '', // If set, overrides default API URL and points to an external URL
)
);

/**
* Array of configuration settings. Amend each line as needed.
* If you want the default strings to be available under your own theme domain,
* leave the strings uncommented.
* Some of the strings are added into a sprintf, so see the comments at the
* end of each line for what each argument will be.
*/
$config = array(
'domain' => $theme_text_domain, // Text domain - likely want to be the same as your theme.
'default_path' => '', // Default absolute path to pre-packaged plugins
'parent_menu_slug' => 'themes.php', // Default parent menu slug
'parent_url_slug' => 'themes.php', // Default parent URL slug
'menu' => 'install-required-plugins', // Menu slug
'has_notices' => true, // Show admin notices or not
'is_automatic' => false, // Automatically activate plugins after installation or not
'message' => '', // Message to output right before the plugins table
'strings' => array(
'page_title' => __( 'Install Required Plugins', $theme_text_domain ),
'menu_title' => __( 'Install Plugins', $theme_text_domain ),
'installing' => __( 'Installing Plugin: %s', $theme_text_domain ), // %1$s = plugin name
'oops' => __( 'Something went wrong with the plugin API.', $theme_text_domain ),
'notice_can_install_required' => _n_noop( 'This theme requires the following plugin: %1$s.', 'This theme requires the following plugins: %1$s.' ), // %1$s = plugin name(s)
'notice_can_install_recommended' => _n_noop( 'This theme recommends the following plugin: %1$s.', 'This theme recommends the following plugins: %1$s.' ), // %1$s = plugin name(s)
'notice_cannot_install' => _n_noop( 'Sorry, but you do not have the correct permissions to install the %s plugin. Contact the administrator of this site for help on getting the plugin installed.', 'Sorry, but you do not have the correct permissions to install the %s plugins. Contact the administrator of this site for help on getting the plugins installed.' ), // %1$s = plugin name(s)
'notice_can_activate_required' => _n_noop( 'The following required plugin is currently inactive: %1$s.', 'The following required plugins are currently inactive: %1$s.' ), // %1$s = plugin name(s)
'notice_can_activate_recommended' => _n_noop( 'The following recommended plugin is currently inactive: %1$s.', 'The following recommended plugins are currently inactive: %1$s.' ), // %1$s = plugin name(s)
'notice_cannot_activate' => _n_noop( 'Sorry, but you do not have the correct permissions to activate the %s plugin. Contact the administrator of this site for help on getting the plugin activated.', 'Sorry, but you do not have the correct permissions to activate the %s plugins. Contact the administrator of this site for help on getting the plugins activated.' ), // %1$s = plugin name(s)
'notice_ask_to_update' => _n_noop( 'The following plugin needs to be updated to its latest version to ensure maximum compatibility with this theme: %1$s.', 'The following plugins need to be updated to their latest version to ensure maximum compatibility with this theme: %1$s.' ), // %1$s = plugin name(s)
'notice_cannot_update' => _n_noop( 'Sorry, but you do not have the correct permissions to update the %s plugin. Contact the administrator of this site for help on getting the plugin updated.', 'Sorry, but you do not have the correct permissions to update the %s plugins. Contact the administrator of this site for help on getting the plugins updated.' ), // %1$s = plugin name(s)
'install_link' => _n_noop( 'Begin installing plugin', 'Begin installing plugins' ),
'activate_link' => _n_noop( 'Activate installed plugin', 'Activate installed plugins' ),
'return' => __( 'Return to Required Plugins Installer', $theme_text_domain ),
'plugin_activated' => __( 'Plugin activated successfully.', $theme_text_domain ),
'complete' => __( 'All plugins installed and activated successfully. %s', $theme_text_domain ), // %1$s = dashboard link
'nag_type' => 'updated' // Determines admin notice type - can only be 'updated' or 'error'
)
);
tgmpa( $plugins, $config );
}